Preparation method of waterproof and wear-resistant TPU and its application in zippers

Abstract

The present invention relates to the field of polyurethane technology, and discloses a preparation method of a waterproof and wear-resistant TPU and its application in a zipper. The present invention reacts a polyester polyol and a diisocyanate monomer, then adds 1,4-butanediol and a polyhydroxy monomer, pours the mixture into a mold, vulcanizes the mixture after demoulding, and then mixes it with modified silica, extrudes it, and pelletizes it to obtain a waterproof and wear-resistant TPU. The present invention introduces a large amount of long alkyl chains on the surface of nano-silica, improves dispersibility, reduces agglomeration, and improves compatibility with polyurethane, so that the nano-silica is evenly dispersed in the polyurethane matrix, significantly improving the tensile properties, wear resistance, and waterproof properties of the TPU material.

Description

Technical Field

[0001] The present invention relates to the technical field of polyurethane, in particular to a preparation method of waterproof and wear-resistant TPU and application of the same in zippers. Background Art

[0002] Polyurethane (PU) boasts excellent elasticity, heat resistance, oil resistance, and aging resistance, making it widely used in shoe soles, zipper teeth, foam sheets, and packaging materials. Filling and modifying PU is crucial for improving its mechanical strength, wear resistance, and water resistance. Common fillers include nanosilica, carbon fiber, calcium carbonate, and aluminum oxide.

[0003] Nanosilica is a high-performance nanomaterial that is inexpensive, readily available, mechanically strong, stable, and easily surface-modified. It is widely used in polymer materials such as polyurethane, typically requiring the use of silane coupling agents, stearic acid, hexadecanol, polyethylene glycol, and the like. Chinese Patent Publication No. CN115852703A discloses a modified nanosilica-reactive polyurethane cross-linked waterproofing agent and its preparation method. The modified nanosilica, produced by modifying nanosilica with long-chain alkylsilane coupling agents and azidosilane coupling agents, is reacted with reactive polyurethane to produce a modified nanosilica-reactive polyurethane cross-linked hydrophobic compound, which can be used in waterproofing cotton and synthetic fabrics. However, this patent fails to improve the mechanical properties and wear resistance of the polyurethane material. Summary of the Invention

[0004] The invention solves the problem that the polyurethane material has poor water resistance, mechanical properties and wear resistance.

[0005] Technical solution: A method for preparing waterproof and wear-resistant TPU:

[0006] Step S1, adding nano-silica to water, ultrasonically dispersing, adding sodium hydroxide, stirring at 85-90° C. for 2-3 hours, then adding dilute hydrochloric acid to adjust the pH to 8-9, adding a polyhydroxy monomer, stirring for 2-5 hours, filtering, washing with n-butanol and water in sequence, and drying to obtain modified silica.

[0007] Step S2, mixing the dried polyester polyol and diisocyanate monomer, reacting at 65-75 ° C for 2-3 hours, then adding 1,4-butanediol and polyhydroxy monomer, stirring and mixing, and quickly pouring into a mold at 110-120 ° C, demolding after 1-2 hours, and then vulcanizing at 100-110 ° C for 12-18 hours. The obtained polyurethane product is crushed and mixed with modified silica in a mixer at a mass ratio of 100: (1-6). Extrusion is carried out through an extruder at an extrusion temperature of 175-185 ° C and a screw speed of 100-150 r / min, and pelletizing is performed to obtain waterproof and wear-resistant TPU.

[0008] Preferably, the mass ratio of nano-silica to polyhydroxy monomer in S1 is 100:(4-10).

[0009] Preferably, in step S2, the molar ratio of polyester polyol, diisocyanate, 1,4-butanediol, and polyhydroxy monomer is 1:(2.8-3.2):(1.2-1.7):(0.3-0.8).

[0010] Preferably, the diisocyanate is toluene-2,4-diisocyanate or diphenylmethane-4,4'-diisocyanate.

[0011] Preferably, the preparation method of the polyhydroxy monomer comprises the following steps:

[0012] Step (1): adding ethanolamine and alkyl chloride in a molar ratio of (1-1.1):1 to ethanol, heating to 75-80°C, reflux under condensation for 24-30 hours, rotary evaporation, separation and purification by silica gel column chromatography, and gradient elution with dichloromethane and methanol solution to obtain alkylethanolamine. The reaction formula is:

[0013]

[0014] Step (2): add alkylethanolamine and 1,4-bis(oxyglycidyl)benzene in a molar ratio of (2-2.4):1 to ethanol, react at 50-65°C for 18-24 hours, rotary evaporate, separate and purify by silica gel column chromatography, and perform gradient elution with dichloromethane and methanol solution to obtain a polyhydroxy monomer. The reaction formula is:

[0015]

[0016] Preferably, the alkyl chloride in step (1) is any one of 1-chlorodecane, 1-chlorododecane, 1-chlorotetradecane and 1-chlorohexadecane.

[0017] Preferably, waterproof and wear-resistant TPU is used in zipper teeth.

[0018] Technical effect of the present invention: The present invention utilizes a polyhydroxy monomer to replace part of 1,4-butanediol as a chain extender, which contains multiple hydroxyl polymerization sites, thereby increasing the molecular chain cross-linking density of the polyurethane, which is beneficial to improving the tensile strength and reducing the wear volume. In addition, the polyhydroxy monomer contains a flexible alkyl long chain, which inhibits the accumulation of the polyurethane hard segment, has a certain plasticizing effect, improves the elongation at break, and makes the TPU have better tensile properties and wear resistance.

[0019] The polyhydroxy monomer of the present invention contains a hydrophobic long alkyl chain, which is introduced into the polyurethane molecular chain, significantly improving the hydrophobicity and water contact angle of the TPU material, and is beneficial to improving the waterproof performance of the TPU material.

[0020] The polyhydroxy monomer of the present invention contains multiple hydroxyl groups and has a strong interaction force with the surface of nano-silica, thereby realizing surface modification of the nano-silica and introducing a large number of long alkyl chains on the surface, thereby improving dispersibility and reducing agglomeration. The polyhydroxy monomer is then blended and extruded with polyurethane. Since the polyurethane also contains the same long alkyl chains, the compatibility between the nano-silica and the polyurethane is improved, and the nano-silica is more evenly dispersed in the polyurethane matrix, thereby playing a better reinforcing role and significantly improving the tensile properties and wear resistance of the TPU material. DETAILED DESCRIPTION

[0021] To facilitate those skilled in the art to understand the technical solution of the present invention, the technical solution of the present invention is further described in conjunction with specific embodiments.

[0022] Polyester polyol, molecular weight 2000, Xuzhou Yihuiyang New Materials Co., Ltd. Nanosilica, average particle size 20 nm, Guangzhou Hongwu Materials Technology Co., Ltd.

[0023] Example 1:

[0024] (1) Add 40 mmol ethanolamine and 40 mmol 1-chlorohexadecane to 100 mL ethanol, heat to 80°C, reflux under condensation for 24 hours, rotary evaporate, separate and purify by silica gel column chromatography, and perform gradient elution with dichloromethane and methanol solution to obtain alkylethanolamine.

[0025] (2) Add 66 mmol alkylethanolamine and 30 mmol 1,4-bis(oxyglycidyl)benzene to 200 mL of ethanol, react at 60°C for 24 h, rotary evaporate, separate and purify by silica gel column chromatography, and perform gradient elution with dichloromethane and methanol solution to obtain a polyhydroxy monomer.

[0026] (3) Add 5 g of nano-silica to 200 mL of water, disperse by ultrasonication, add 40 mg of sodium hydroxide, stir at 90 ° C for 2 h, then add dilute hydrochloric acid to adjust the pH to 9, add 0.2 g of polyhydroxy monomer, stir for 2 h, filter, wash with n-butanol and water in turn, and dry to obtain modified silica.

[0027] (4) 100 mmol of dry polyester polyol and 300 mol of diphenylmethane-4,4'-diisocyanate were mixed and reacted at 65 °C for 3 h, then 170 mmol of 1,4-butanediol and 30 mmol of polyhydroxy monomer were added, stirred and mixed, and quickly poured into a mold at 110 °C, demolded after 1 h, and then vulcanized at 110 °C for 12 h. The obtained polyurethane product was crushed and mixed with modified silica in a mixer at a mass ratio of 100:1, extruded through a twin-screw extruder at an extrusion temperature of 180 °C and a screw speed of 150 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0028] Example 2:

[0029] (1) Add 40 mmol ethanolamine and 40 mmol 1-chlorodecane to 150 mL ethanol, heat to 75 ° C, reflux under condensation for 30 hours, rotary evaporate, separate and purify by silica gel column chromatography, and use dichloromethane and methanol solution for gradient elution to obtain alkylethanolamine.

[0030] (2) Add 60 mmol alkylethanolamine and 30 mmol 1,4-bis(oxyglycidyl)benzene to 200 mL of ethanol, react at 50°C for 24 hours, rotary evaporate, separate and purify by silica gel column chromatography, and perform gradient elution with dichloromethane and methanol solution to obtain a polyhydroxy monomer.

[0031] (3) Add 5 g of nano-silica to 250 mL of water, disperse it ultrasonically, add 52 mg of sodium hydroxide, stir it at 85 ° C for 3 h, then add dilute hydrochloric acid to adjust the pH to 8, add 0.35 g of polyhydroxy monomer, stir it for 5 h, filter it, wash it with n-butanol and water in turn, and dry it to obtain modified silica.

[0032] (4) 100 mmol of dried polyester polyol and 280 mol of diphenylmethane-4,4'-diisocyanate were mixed and reacted at 65 °C for 3 h, and then 140 mmol of 1,4-butanediol and 60 mmol of polyhydroxy monomer were added. After stirring and mixing, they were quickly poured into a mold at 110 °C, demolded after 2 h, and then vulcanized at 100 °C for 18 h. The obtained polyurethane product was crushed and mixed with modified silica in a mixer at a mass ratio of 100:3. It was extruded through a twin-screw extruder at an extrusion temperature of 175 °C and a screw speed of 100 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0033] Example 3:

[0034] (1) Add 44 mmol ethanolamine and 40 mmol 1-chlorotetradecane to 150 mL ethanol, heat to 80 ° C, reflux under condensation for 24 hours, rotary evaporate, separate and purify by silica gel column chromatography, and use dichloromethane and methanol solution for gradient elution to obtain alkylethanolamine.

[0035] (2) Add 72 mmol alkylethanolamine and 30 mmol 1,4-bis(oxyglycidyl)benzene to 300 mL of ethanol, react at 65°C for 18 h, rotary evaporate, separate and purify by silica gel column chromatography, and perform gradient elution with dichloromethane and methanol solution to obtain a polyhydroxy monomer.

[0036] (3) Add 5 g of nano-silica to 250 mL of water, disperse by ultrasonication, add 65 mg of sodium hydroxide, stir at 90 ° C for 2 h, then add dilute hydrochloric acid to adjust the pH to 9, add 0.5 g of polyhydroxy monomer, stir for 5 h, filter, wash with n-butanol and water in turn, and dry to obtain modified silica.

[0037] (4) Mix 100 mmol of dried polyester polyol and 320 mol of toluene-2,4-diisocyanate, react at 65-75°C for 2-3 hours, then add 120 mmol of 1,4-butanediol and 80 mmol of polyhydroxy monomer, stir and mix, and quickly pour into a mold at 120°C, demould after 1 hour, and then vulcanize at 100°C for 18 hours. The obtained polyurethane product is crushed and mixed with modified silica in a mixer at a mass ratio of 100:6. It is extruded through a twin-screw extruder at an extrusion temperature of 185°C and a screw speed of 100 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0038] Comparative Example 1:

[0039] (1) 100 mmol of dried polyester polyol and 300 mol of diphenylmethane-4,4'-diisocyanate were mixed and reacted at 65 °C for 3 h, then 200 mmol of 1,4-butanediol was added, stirred and mixed, and then quickly poured into a mold at 110 °C, demoulded after 1 h, and then vulcanized at 110 °C for 12 h. The obtained polyurethane product was crushed and mixed with nano-silica in a mixer at a mass ratio of 100:1, extruded through a twin-screw extruder at an extrusion temperature of 180 °C and a screw speed of 150 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0040] Comparative Example 2:

[0041] (1) 100 mmol of dried polyester polyol and 300 mol of diphenylmethane-4,4'-diisocyanate were mixed and reacted at 65 ° C for 3 hours, and then 170 mmol of 1,4-butanediol and 30 mmol of polyhydroxy monomer (prepared by Example 1) were added, stirred and mixed, and then quickly poured into a mold at 110 ° C, demoulded after 1 hour, and then vulcanized at 110 ° C for 12 hours. The obtained polyurethane product was crushed and mixed with nano-silica in a mixer at a mass ratio of 100:1, extruded through a twin-screw extruder at an extrusion temperature of 180 ° C and a screw speed of 150 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0042] Comparative Example 3:

[0043] (4) 100 mmol of dried polyester polyol and 300 mol of diphenylmethane-4,4'-diisocyanate were mixed and reacted at 65 ° C for 3 h, and then 200 mmol of 1,4-butanediol was added. After stirring and mixing, the mixture was quickly poured into a mold at 110 ° C, demolded after 1 h, and then vulcanized at 110 ° C for 12 h. The obtained polyurethane product was crushed and mixed with modified silica (prepared in Example 1) in a mixer at a mass ratio of 100:1, extruded through a twin-screw extruder at an extrusion temperature of 180 ° C and a screw speed of 150 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0044] Comparative Example 4:

[0045] (1) Add 5 g of nano-silica to 200 mL of water, disperse by ultrasonication, add 40 mg of sodium hydroxide, stir at 90 ° C for 2 h, then add dilute hydrochloric acid to adjust the pH to 9, add 0.2 g of 1-hexadecanol, stir for 2 h, filter, wash with n-butanol and water in sequence, and dry to obtain modified silica.

[0046] (2) 100 mmol of dried polyester polyol and 300 mol of diphenylmethane-4,4'-diisocyanate were mixed and reacted at 65 ° C for 3 hours, and then 170 mmol of 1,4-butanediol and 30 mmol of polyhydroxy monomer (prepared by Example 1) were added, stirred and mixed, and then quickly poured into a mold at 110 ° C, demoulded after 1 hour, and then vulcanized at 110 ° C for 12 hours. The obtained polyurethane product was crushed and mixed with modified silica in a mixer at a mass ratio of 100:1, extruded through a twin-screw extruder at an extrusion temperature of 180 ° C and a screw speed of 150 r / min, and pelletized to obtain waterproof and wear-resistant TPU.

[0047] The TPU was molded in a flat vulcanizer at 10 MPa and 180°C for 10 min to prepare a test specimen.

[0048] Tensile properties were tested according to GB / T 528-2009. Akron abrasion volume and wear resistance were tested according to GB / T 1689-2014.

[0049] The sample was pressed into a thin film sample, and the water contact angle was tested according to GB / T 30693-2014 standard.

[0050] Table 1 TPU performance test

[0051]

[0052] In Comparative Example 1, 1,4-butanediol was used as a chain extender to co-extrude the resulting polyurethane with nano-silica. The resulting TPU exhibited low tensile strength and elongation at break, a large Akron abrasion volume, poor tensile and wear resistance, a small water contact angle, and poor water and water resistance. This was primarily due to poor dispersibility of the nano-silica, which easily agglomerated within the polyurethane matrix, and poor compatibility with the polyurethane, resulting in poor tensile and wear resistance.

[0053] Comparative Example 2 uses a polyhydroxy monomer to replace part of 1,4-butanediol as a chain extender. The tensile strength and elongation at break of the obtained TPU material increase, the Akron abrasion volume decreases, and the water contact angle increases, and the tensile properties, wear resistance and waterproof properties improve. This is because the polyhydroxy monomer contains multiple hydroxyl polymerization sites, which increases the cross-linking density of the polyurethane molecular chain, which is beneficial to improving the tensile strength and reducing the abrasion volume. In addition, the polyhydroxy monomer contains flexible alkyl long chains, which inhibit the accumulation of polyurethane hard segments and have a certain plasticizing effect, thereby improving the elongation at break and giving the TPU better tensile properties and wear resistance. In addition, the alkyl long chain has strong hydrophobicity. When introduced into the polyurethane molecular chain, it significantly improves the hydrophobicity and water contact angle of the TPU material, which is beneficial to improving the waterproof performance.

[0054] Compared with Comparative Example 1, the nano-silica in Comparative Example 3 has better dispersibility after being modified with a polyhydroxy monomer, and reduces agglomeration, which is beneficial to improving the tensile properties and wear resistance of the TPU material.

[0055] In Example 1-3, a polyhydroxy monomer was used to replace part of the 1,4-butanediol as a chain extender and co-extruded with modified silica. The resulting TPU exhibited improved tensile and wear resistance. This is because the polyurethane contains long alkyl chains, which are also present on the surface of the modified silica. This improves the compatibility between the nano-silica and the polyurethane, allowing the nano-silica to be more evenly dispersed in the polyurethane matrix, thus providing a better reinforcement effect and further improving the tensile and wear resistance of the TPU material. It also exhibits excellent water resistance.

[0056] Compared with Example 1, Comparative Example 4 uses hexadecanol as a modifier to modify the surface of nanosilica, introduces long alkyl chains on the surface, and improves its compatibility with polyurethane. The tensile properties and wear resistance of the polyurethane are good, but the tensile strength and elongation at break are lower than those in Example 1, and the wear volume is higher than that in Example 1. This is mainly because hexadecanol contains only one hydroxyl group, and the interaction force with the surface of nanosilica is low, and the modification effect is poor. The polyhydroxy monomer in Example 1 contains multiple hydroxyl groups, and the interaction force with the surface of nanosilica is stronger, and the modification effect is very good. More long alkyl chains can be introduced on the surface of nanosilica to further enhance the compatibility with polyurethane, thereby exerting a better reinforcement effect.

[0057] The technical solution of the present invention is described above in conjunction with the embodiments. Obviously, the specific implementation of the present invention is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the invention are directly applied to other occasions without improvement, they are all within the scope of protection of the present invention.

Claims

1. A method for preparing waterproof and wear-resistant TPU, characterized in that: The steps include: Step S1, adding nano-silica to water, ultrasonically dispersing, adding sodium hydroxide, stirring at 85-90° C. for 2-3 hours, then adding dilute hydrochloric acid to adjust the pH to 8-9, adding a polyhydroxy monomer, stirring for 2-5 hours, filtering, washing, and drying to obtain modified silica; Step S2, mixing dried polyester polyol and diisocyanate monomer, reacting at 65-75°C for 2-3h, then adding 1,4-butanediol and polyhydroxy monomer, stirring and mixing, pouring into a mold at 110-120°C, demolding after 1-2h, and then vulcanizing at 100-110°C for 12-18h, crushing the obtained polyurethane product, mixing it with modified silica in a mass ratio of 100:(1-6) in a mixer, extruding through an extruder, and pelletizing to obtain waterproof and wear-resistant TPU; The preparation method of the polyhydroxy monomer comprises the following steps: Step (1), adding ethanolamine and alkyl chloride in a molar ratio of (1-1.1):1 to ethanol, heating to 75-80°C, condensing and refluxing for 24-30h, rotary evaporation, and separation and purification by silica gel column chromatography to obtain alkylethanolamine; Step (2), adding alkylethanolamine and 1,4-bis(oxyglycidyl)benzene to ethanol, rotary evaporation after the reaction, and separation and purification by silica gel column chromatography to obtain a polyhydroxy monomer; In the step (1), the alkyl chloride is any one of 1-chlorodecane, 1-chlorododecane, 1-chlorotetradecane, and 1-chlorohexadecane; In the step (2), the molar ratio of alkylethanolamine to 1,4-bis(oxyglycidyl)benzene is (2-2.4):

1.

2. The method for preparing waterproof and wear-resistant TPU according to claim 1, characterized in that: In the step S1, the mass ratio of nano-silica to polyhydroxy monomer is 100:(4-10).

3. The method for preparing waterproof and wear-resistant TPU according to claim 1, characterized in that: In step S2, the molar ratio of polyester polyol, diisocyanate, 1,4-butanediol, and polyhydroxy monomer is 1:(2.8-3.2):(1.2-1.7):(0.3-0.8).

4. The method for preparing waterproof and wear-resistant TPU according to claim 3, characterized in that: The diisocyanate is toluene-2,4-diisocyanate or diphenylmethane-4,4'-diisocyanate.

5. The method for preparing waterproof and wear-resistant TPU according to claim 1, characterized in that: The reaction temperature in step (2) is 50-65° C., and the reaction time is 18-24 h.

6. The method for preparing waterproof and wear-resistant TPU according to claim 1, characterized in that: In step S2, the extrusion temperature of the twin-screw extruder is 175-185° C., and the screw speed is 100-150 r / min.

7. Use of the waterproof and wear-resistant TPU obtained by the preparation method according to any one of claims 1 to 6 in a zipper.

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